It's suggested to always replace the bolt when it has been removed. If you're already doing a big job like the timing belt and extras... why not spend another $8 to follow manufacturer's instructions?
They recommend replacing the timing belt idler pulley bolt, but that is different from the front crankshaft damper bolt. Again, unless that crankshaft damper bolt has been torqued past the yield point and has permanently stretched, there is no need to replace it. And I am certain that it has not been torqued to the point where it is permanently stretched.
I would actually worry more about torqueing that bolt properly than replacing it. The easiest way to torque it is to use an air impact wrench with a torque extension. You do not want to wedge a steel bar or a long screwdriver into spokes of crankshaft damper to hold it in place while tightening the bolt, as you can shear the rubber ring inside the damper. They actually make special tools to hold the damper in place while manually torqueing the bolt, but these tools are hard to find and are expensive. these tools look like a long bar with a hollow circle welded on the end with holes drilled into the circle so you can bolt that part to the crankshaft pulley and then manually tighten the center bolt through the circle opening in the middle with a torque wrench. I actually have one for Mazda Protégé LX, which I owned many years ago.
BTW, I am getting ready to replace the timing belt on my 2013 Sonic, so I will post any unique experiences after I am done. I am considering replacing the cam front oil seals and the crank front oil seal as well, but they probably will not start leaking until much higher mileage. I used to replace these oil seals with every timing belt change on my 1999 Mazda 626 V6 and what a PITA this was . I actually changed the timing belt on that car 3 times (every 100k miles). I cannot think of a more difficult vehicle to change the timing belt on that this Mazda V6. I actually had to make a special tool to be able to drive the front crank seal in after removing the old one, as there was literally no room to work around that engine. No wonder the dealer charged about $ 600 for labor alone to replace this timing belt.
